I have just installed ubuntu alongside with windows, but I have switched the sizes I wished for their partitions, with windows with about 500GB and ubuntu with about 100GB, though I wanted the other way around.

Can I just change the sizes of the partitions with the boot dvd or I have to format the HDD and do it over again?

Edit:

Allright mates I lauched gparted as required. Thing is have my linux partition inside another one, "extended", which I am not allowed to unmount even when booting from live DVD. In other words, sda4 (the extended) includes sd65 (with ubuntu) and sda5 (the swap).

This happened after second installation process. I don't know why the installation process made that. Anyway, I cannot work with remaking sizes while not unmounting sda4.

2 Answers
2

Yes, you can still resize the partitions using gparted; it's on the Ubuntu installation medium (either DVD or USB) so you can boot into a live session and run gparted, or you can install it in Ubuntu from the Ubuntu Software Center. Gparted has a very good track record with this sort of thing, but anytime you mess with resizing or moving partitions it's best to have a backup of your data.

Of course, if you just did the installation again, just specifying correctly the partitions sizes that you really want, you'll still end up using gparted, so in a way it's the same solution either way.

I just tried to do the installation again, and i was successeful in making one partition smaller, but i couldnt make the other bigger and ended up with lots of free space...
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luccas_lokiApr 19 '13 at 3:20

It's best to do it from the LiveDVD (or USB) session, as you won't be messing with a partition that you're using. If that isn't what you did, go back and boot from the DVD or USB, choose to boot into a live session, and run the gparted that it has (you'll find it in the Dash).
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KelleyApr 19 '13 at 17:16